Catalytic conversion of hydrocarbons



July 18, 1950 P. c. KEITH ETAL CATALYTIC CONVERSION oF HYDRocARBoNs Original Filed April 24, 1941 3 Sheets-Sheet 1 HL KES S cjfwym LWM/A/. an E /L i VHV www3 .A i Q Pd wm.

July 18 1950 P. c. KEITH Erm. 2,515,374

CATALYTIC CONVERSION 0F HYDROCARBONS ATTORN EYS July 18, 1950 P. c. KEITH Er AL CATALYTIC CONVERSION oF HYDRoARBoNs Original Filed April 24, 1941 3 Sheets-Sheet 3 Patented July 18, 1950 CATALYTIC CONVERSION OF HYDROCARB ONS y Percival C. Keith, Peapack, and Joseph W. Jewell, Summit, N. J., assignors to The M. W. Kellogg Company, Jersey City, N. J., a corporation of Delaware Original application April 24, 1941,'Serial No.

390,164. Divided and this 1945, Serial No. 604,788

13 claims. (o1. 19-52) The present application is a division of our co-pending application Serial No. 390,164, filed April 24, 1941.'

Our invention relates to improvements in process and apparatus for effecting catalytic conversions. In its speciiic aspects the invention is directed particularly to an improved continuous process of converting hydrocarbons by treatment over catalytic materials which become spent or deactivated during the conversion, and which accordingly require periodic regeneration treatment to iit them for reuse in the conversion step.

The catalytic conversion of high boiling hydro` carbons such as petroleum gas oil and the like into low boiling hydrocarbons Within the gasoline boiling range is an example` of the latter type of conversion reaction of outstanding importance.

It has been proposed heretofore to catalytically convert high boiling hydrocarbons such as gas oil to low boiling hydrocarbons within the gasoline boiling range by passing vapors of the high boiling hydrocarbons under suitable reaction conditions in contact With a stationary bed of a cracking catalyst disposed in a catalyst chamber. activity of the catalyst is decreased by reason of the formation of a carbonaceous deposit thereon to an extent Where regeneration is necessary or desirable, the activity of the catalyst is restored by stopping the flow of oil vapor to the chamber and passing an oxygen-containing gas into the chamber in contact with the spentcatalyst, thereby regenerating it in situ by combustion of the carbonaceous deposit. Although such processes are commercially practicable they are subject to a number of inherent limitations and disadvantages which are eliminated by the present invention. Among these are. the intermittent nature of the operation, variationsin product Pursuant to such processes, after the l application July 13,

-quality and quantity during the reaction period vand diculty in temperature control, particularly in the regeneration operation.

A process whereby various of the objectionable limitations and disadvantages of the stationary bed or intermittent type of operation are eliminated is describedv in application Serial No. 199,702', led April 2, 1938, by Keith et al., which has now issued as U. S. Patent 2,350,730.- In ac'- cordance with the Keith et al. process continuous operation and uniformity in yield and quality of products in the practice of catalytic reactions such catalytic cracking and the like, is obtained by a procedure wherein the vapors ofthe oil undergoing conversion are passed in contact With a, compact mass or moving bed of catalytic material confined in a reaction zone, and the average catalytic activity of the catalytic mass is maintained substantially constant by adding active catalyst thereto and removing spent catalyst therefrom Without interruption of the iiow of oil vapor through the reaction zone.

In the process disclosed by said Keith et a1. patent, the catalyst is employed in granular'condition and the movement of the catalyst through the conversion zone is effected by gravity flow at regulated rates controlled by suitable mechanical discharging means. Accordingly, the process is subject to certain limitations which are obviated by the present process. The primary object of the present invention is the provision of a process wherein the catalyst is introduced into the conversion and regeneration zones in nely divided or powdered condition and at the same time certain of the variable operating conditions are so controlled as to maintain a suitable concentration of the catalyst in said zones for the desired conversion and regeneration eiiects in an apparatusof feasible dimensions. The various features and advantages of the procized.

3 ess will be evident from the following detailed description thereof given in connection with the appended drawings wherein:

Fig. 1 illustrates diagrammatically a suitable complete process flow and arrangement of apparatus for use in the practice of the invention.

Fig. 2 is an elevation view of the reactor or conversion chamber and the catalyst regeneration chamber or regenerator, and illustrates the details of these elements and their interconnection.

Fig. 3 is a view similar to Fig. 2 of a modified form of reactor and regenerator.

Fig. 4 is a plan view illustrating the details of the baille device.

- The steps of catalytic conversion and regeneration of the catalyst as preferably practiced pursuant to this invention may be more readily understood `by reference to Fig. 2. As indicated thereon, a nely divided or powdered active catalyst is introduced through the outlet l of a catalyst standpipe 3l into a stream of the feed vapors traveling at a relatively 'high velocity through the reactor inlet line 2. Both the :cat-I alyst and vapors preferably are heated prior to their mixture in their line '2 "'to an elevatedutemperature suitable for the subsequentconversiom Vaporized feed may be supplied to line 2 by a transfer line 3 leading from aheater 4 or other suitable source of vaporized feedstock. Catalyst thus introduced is pi'cked'up by the 'vapors and carried therewith through line 2 into a conical inlet 5 in the lower part of reactor `6. Re-

actor 6 is a vessel, in the form of a cylinder or 'other suitable shape, lhaving Ya relatively great .cross-sectional area lcompared -to the ycross-sectional area of the vapor inlet vline -2, -and these vrelative proportionsv cause .a 1corresponding re- .duction in-the velocity of the vapors after vtheir state Imay conveniently be designated as iluidl This uidized condition, j.in general, is characterized by the relatively .high concentra- .tionof .catalyst measured in terms :of the quantity of catalyst per unit volume of Yreactor space, and yby the maintained "low velocity .of reactant vapors through 'the reactor.

`'Ihe reactant vapors travel upwardly through the reactor Tin contact with "the uidized catalyst and dur-ing this `.period of contact undergo .the desired conversion. Operating .conditions .in uthe reactor 'determined by variables such as .the dimensions of the reactor, and the temperatures and rates at which -reactant vapors .andcatalyst are supplied ther-cto, are maintained Within such limits as to .bring about the desiredrquality :and extent of conversion `as -described vin detail hereinafter. y

'The vaporous reaction products are withdrawn from the Yupperpart of thereactor through asuit- It.is contemplated of .decreasing cross-sectional area wherein theirv velocity is .progressively increased Aand then into .an .outlet pipe 48 of relatively restricted -crosssectional area compared 4to thatof the reactor. The Vaporous conversion products .-mixed :with spent catalyst exit through the outlet pipe 8 at a relatively high velocity into a settling chamber or collecting hopper 9 of such cross-sectional area that the velocity of the vapors therein is preferably of about the same order of magnitude but may be more or less than the vapor velocity in reactor 6. A baffle Il), shown in plan in Fig. 4, is preferably interposed directly in the path of the vapor mixture exiting from pipe 8 whereby the mixture is 'directed laterally and downwardly thus functioning to propel catalyst particles present in the mixture out of the path of the vapor flow into a quiescent collecting zone defined by the inner Walls of the outlet cone 1 and outlet pipe 8 and the lower inner walls of the settling or collecting. hopper 9. Catalyst thus separated is withdrawn through suitable means such as catalyst standpipe l I opening into the lower part of the collecting Zone. A quantity of catalyst is preferably lefft .at all times .in said .zone to mainytaina level of catalyst vvtherein vat a substantial distance above the spent catalyst outlet opening -fa's indicated by dotted line l2. Vaporous conversion `products are withdrawn from the upper lgpart Aof the collecting hopper through line I3 mixed with a relatively small portion of the cataly'st originally present in the mixture passing throughpipe. The effectiveness of the separation in chamber as demonstrated hereafter by specic examples, is much greater than that predictable fromtheo'retical conclusions based upon lfa= consideration of's'uch known factors as the parfticlefsi'zesfand settling rate of the catalytic material employed and the fact that the vapor velocity in chamber Q may be ofthe same order of magnitude vas those utilized to .carry the particles 'throughrea'ctor 16.

vvltesidu'al catalyst *left in 'the vaporous 'conversionproducts exiting through. line I3 is'. separated in a suitable 'recovery system described "in 'detail 'hereinafter in A-connection with wthe Fig. "l, and may be returned Jto the "spent'ca'talyst separated in chamber 9 'throughfline v14.

A suitable 'stripping 'medium such as .steam is `introduced'through aline I'Ehaving'suitable liuid 'distributingm'ean's l6,"in the lbottom of the mass of .eatalyst'in the collecting zone to lstrip or dis,- place khydrocarbon vapors absorbed "thereon .or entrained therewith vand 'to maintain the mass v Iinan a'erated 4flowable condition. While only one such -litre :I`5 for "introduction of thestrpping medium is shown, 'it is .tob'e understood that -any suitable'number may -be employed yan'dbe ,so .distributed throughout the collecting chamber as to "assure the required .stripping 'and aerating i effects. Y'The"quantityofstripping steam is prferably "such 'that' itsvelocity the 'collecting zone is low, that is, vof the -order of about .0.1 "to 0;3 "feet per "'se'con'tl. :The 'stripping medium and stripped 'oil vapors pass 1' out 'of chamber `9 over- 7l'leadthrough line ll3`together `with'the vaporous conversion products.

-As illustrative -of 'the operating conditions preferably'maintained 'inthe reaction zone reference lis yma-de to the ldata tabulated in the `following -Tables l-iA-and-l-. wherein Table l--Arepre- --sents conditions suitable foraiarge scale comrmercial unit )for a given type ofc'harging stock "and capacity, and 'Table `l--"-B, contains Adata 'obtained .in the 'operation -fo`f a -unit -on..a'pilot 4plant'or'laboratoryscale.

Reactor dimensions (b), da., ft..-...........

"l'hefmixture ofhot spent catalystV and carrying medium ows through line I9 into an inlet cone Feed weight ratio of catalyst to oil y Reactor temperature, inlet cone 5, F 933 20 at the bottom of the `regenerator 2l where it Reactor temperature, outlet cone 1, F 900 meets and mixes with a stream of relativelycool Reactor pressure, inlet cone 5, lbs/sq. in 13.0 5 recycled'regenerated catalyst and air from cooler ReaCtDI' Dlesul?, 011171813 C0118 7. lbS-/Sfl-HL- 9-5 22 and passs therewith upwardly through the re- Vapo' Velolty lmet ft-/Sec generation chamber 2|.l Operating conditions in Zagor Vlocltylgutet tg-----g--E 2' the regeneration chamber or zone 2l are prefera' lo o Welg 0 01 e r o W o ably maintained to provide acondition similar to s catalyst in reactor (w./hr./w.) 2.6 10 Oil Vapor, Contact time *seconds 13 6 that maintained in the reaction zone with respect i Catalyst time seconds "M290 to a luidized condition of the catalyst. This 3 Catalyst concentration, lbs./cu. ft.; condition similar to that maintained in there- (a) met une 2 0 98 actor is characterized by the relatively large conv (o) Reactor 18.0 15 centration of catalyst and low vapor velocities (c) Reactor outlet, 1ine'8 0.6 maintained in the regeneration zone. During'the TABLE l-B Run Number 5254 5325.4 5320.1 5205 5335.1 5335.5

011 reed, Leers/Hr. (31.1 API Gas 011)-. 11. 7 15. o 15. 2 19. s 15. 7 15.7 Steam Feed, Mol Per Cent 59. 7 61.3 60.4 58.3 58. 9 62.9 Reactor Dimensions:

(a) rin-Ff 12 12 12 12 12 12 (5) Dia-in 2.5 2.5 2.5 2.5 2.5 2.5 weight Feed Ratio'of Catalyst 5o ou 4. o 3.1 3. 5 2.1 Reactor Temperature, Average F 900 900 895 900 985 985 Reactor Pressure, Average, Lbs/Sq. In 10. 5 r10. 5 v 9. 5 9. 5 11. 5 10.5 vapor vemeuy, inlet, 1in/see f 1.13 1. 43 1. 54 2.03 1. 53 1.75 vapor velocity, outlet, 13e/spp 1. s2 2. 22 2. 24 y 2. 52 2. 5s 2. 87 Ratio of Weight of Oil Fed/Hr. to Wt of CatalystinReactorW./Hr./W- 3.8 6.4 8.0 13.5 8.3 7.4 Oil Vapor, contact time, seconde 8 6. 5 6.4 5. 2 5. 8 5. 2 Catalyst Time, Seconds 240 360 126 126 168 114 Catalyst Concentration, Lbs/Cu. Ft.:

(a) mei 0.75 0. 5s 0.55 0.37 0.49 0.71 (5) www 17.0 12.8 10.3 7.9 10.3 11.5 Yields:

(a) Gasoline, v51. Per Cent 47.1. 43.3 43.5. 31.4 43.9 48.3 Fame Burana 4.6 2.6 3.4 1.2 5.5 7.1 (c) cycle 011.- 47.0 54.3 52.5 55.5 49.2 42.0 (d) Gas, Wt, Per Cpnl' 4. 1 3. 2 3. 2 1. 8 5. 7 6. 7 (e) Carbon.- 5. l 3.5 4.4 1.9 3.5 4.4 (j) Gasoline Octane No 79. 1 79. 9 80.7 8l. 7 80. 6

In conveying the spent catalyst from the spent catalyst collecting zone to the regeneration zone suitable provision is made for any difference in pressure between these zones. A somewhat higher pressure is normally preferably maintained in v i course of the travel of the spent catalyst upthe bottom or inlet portion of the regeneration zone than the pressure maintained in the collecting zone, and a head of suitably aerated or iluidized catalyst is preferably maintained in the outlet standpipe Il of a suflicient magnitude to y balance or exceed this differential pressure. For this purpose spent catalyst flowing through standpipe ll is maintained in a condition in which it has the flow characteristics of a liquid by introducing in suitably regulated amounts an aerating medium such as steam through lines I'I'at the bottom of and at other suitably spaced points along the length of pipe Il.

From the bottom of standppe l I spent catalyst is fed under the influence of the pressure head maintained therein and the pressure head provided by the mass of aerated catalyst in chamber 9 through a suitable feeding means such as a slide valve I8 into the regenerator inlet line i9.

Spent catalyst thus introduced is mixed with air or other suitable carrying medium such as steam introduced into pipe I9 by line 20. In case air is employed, the quantity introduced is so controlled that the combustion of the spent catalyst in line I9 is not sufficient to raise the temperature of the catalyst beyond the maximum wardly through regeneration chamber 2l comlbustion of the carbonaceous deposit thereon is effected to the required extent at an elevated temperature maintained below the safe maximum regeneration-temperature by means of the cooled recycled catalyst.

Gaseous regeneration products (flue gas) and regenerated catalyst exit from the upper part of the regenerator through an outlet 23 and into a separator 24 similar in design and mode of operation to separator 9 described in connection with the reactor. The major portion `of the regenerated catalyst is separated and collected in a collecting zone at the bottom portion of the regenerated catalyst collecting hopper or separator 24 and the gaseous combustion Iproducts together with a relatively small amount of regenerated catalyst pass out overhead from chamber 24 throughline 25 to a suitable recovery system such as that illustrated by and hereinafter described in connection with Fig. l. Catalyst recovered from the vapors in line 25 may suitably be returned to hopper 24 through line 26.

Suitable means 21 and 29, similar to pipe l5 vand distributor i6, are provided in the lower portion of hopper 24 to introduce a suitable medium such as steam to strip and displace ilue gas absorbed or entrained with the regenerated catalyst andmaintain the separated catalyst in-an aerated flowable state. As in the case of the reactor a level of separated catalyst indicatedby dotted line..29ds@preferablymaintained ata-substantial 'TABLE 2`A distance Yabove the .catalyst outlet. lines. J Y

Regenerated catalyst is-preferably .withdrawn Spent catalyst, 1bs./hr `632,840 fromseparator-.Nin a splitstream, aporton be- Cooled recycledcatalyst,lbs/hr 1,750,000 ingsentthrough regeneratedeatalyst.recycle line 5 Ratio by weight recycled/spent 2.77 30,A and another portion through regenerated cat-` Inlet temperature, spent catalyst, F v900 al y`st`line"1 'lv leading'to theconversion or reaction Inlet temperature, recycled catalyst,-F 840 system. l'Both catalyst outlet lines 30 and 3| Temperature, mixture .recycled and l are `Apressure sta-ndpipes'similar yto -standpipe I'I spent catalyst, F v850 in that they -are provided with .means -for introlo Temperature, regeneratlon chamber, ducing .an .aerating .medium at `suitable fpoints "F A-1,000 along theirflengthgso/as-.to `:Inaintainthe catalyst Regeneration dnnensions: flowing therethrough :in acondition-.wherein it (a) Height, ft 50 has the .flow I characteristics .of a liquid, .such (b) Dia., ft 18 meansvheing lines 32 leading into recycleline 15 Regeneration velocity: y and ^.lines .-33 .leading to .catalyst Voutlet line 3l. (a) "Base 1.62 The quantity of catalyst Withdrawn and recycled (b)"Top 2.59 through lline is preferably maintained Within Air feed,1bs./hr 88,350 predetermined limits so as to maintain the tem- .Catalyst concentratlon, lbs/cu. ft.: perature in regeneration zone 2| within required 20 (a) Regenerator 20.0 limits in accordance With the principles of operai (D) Outlet vline 1.02 tion described in U. $2,253,486 t0 Arnold Bel- Weight percent of coke based on 011 chetz, dated August 19, 1941. feed 4.85 Regenerated recycle catalyst is 'fed from the Coke percent by wt. on spent catalyst-.. 1.3 bottom of standpipe 30 through a suitable feed- 25 Carbon percent Vby Wt. O11 regenerated ing means such as a slide v alve 34 into an inlet .catalyst 0;'7 line 35 leading to a heat exchanger or catalyst Catalyst contact time, seconds v352 recycle cooler 22. Regenerated catalystthus in- Pressure in regenerator, lbs/sq. in.: troduced is picked up by-air introduced into line (a) Inlet cone 1'6 35 through une 3 6, the quantity of air .thus in- 30 (b) outlet cone 9 TABLE A2--B Run Numb 5264 5325.4 5320.1 52415 `5336.1 5336.5

'Spent Catalyst. Lbs/Hr 9 0 90 105y 80 79 131 Temperature, Regeneration Chamber, E 1,050 1,030 1,045 l 010 1,010 1,025 `Regenerator Dimensions:

(a) Height, Ff 12 12 12 24 12 12 (b) Diameter, In 4 4 4 3 4 4 Regenerator Gas Velocity:

(a) a 1.52 1.38 1. 7s 1. e2 1.34 1.36 (b)'Ton 1.67 1.51 1.43 ,1.73 1.35 1.42 Catalyst Concentration, Lbs/C11. Ft:

(a) nner .0.19. 0.21` v0.24 0.28 0.19 .0.130 (o) Regenerator 12.4 l2.4 10.0 9.6 11.2 12.1 Wt. Per Cent of Coke Based on Oil Feed 5.1 3. 5 4. 4 1.9 3. 5 4.4 GokePer Cent by Wt. on Spent Catalyst .1.163. 1.57 .1. 78. ,1. 41 1. 73 1.35 Carbon Per Cent by Wt,.on Regenerated Catalyst 0. 40 0.47 0.- 58 0. 53 0. 47 0.38 Catalyst Contact Time, Seconds 530 530 "366 '540 540 350 Pressurein Begenerator, Lbs/Sq. Iny11.0 12.5. 12. 5. 12.35 .13.5 13.5

tro'duced being suflcient "together with-'any -air introduced through line 20 to Veffect combustion to the required extent inthe regenerator '2L From line '35 kthe'mixture of air and regenerated` described.

To illustrate yoperati-ng conditions vpreferably maintained in the regeneration zone,reference is made 'to the data ytabulated in `the following Tables 2-A and 2--B wherein -regeneration'zone operating conditions are showncorrespon'ding to the conversion lruns tabulated in Tables 1-A A preferred system `forthe'recovery of residual catalyst present in the overhead .product :from Vseparators 2e is illustrated in Fig. -1. Referring to-this figure gaseous regenerationproducts mi-Xed with a relatively small lportion of the catalyst originally present therein are withdrawn from the upper part .of hopper 24 'through line2-5and pass to a series of separati-ng zones constituted -by suitable gas-solids separators such Kas cyclones, Cottrell precipitators, lters, or the dike, therecovered- -rnaterial being eventually returned -to hopper '24.through line 26.

The gaseous suspension in outlet pipe 25 oon v sists essentially of flue gas and residual suspended regenerated catalyst including-both relatively ne and relatively coarse particles. This suspension is preferably supplied to the recovery system ata superatmospheric pressure suiiicientlr high to yimpel it completely therethrough and into the atmosphere from the final separating zone, the pressure in the successive separating zonesbeing progressively lower 'in `the direction of 'the 110W ci.'

the suspension by reason of the pressure drop in the interconnecting lines and gas-solids separating means. Incidental to such separation it has been ascertained that classification and segregation of the particles occur, particularly segregation of the extremely fine particles in the nal separating zone, this zone being ya Cottrell precipitator as shown, or any other suitable means utilized for the separation of the last increment of the suspended particles.

In certain instances cooling yof the gaseous suspension passing through line 25 may be desirable, as for example by passing it through a suitable cooler or heat exchanger 45 through which 'a heat exchange medium is circulated through lines 46 and 41, thereby effecting a reduction in temperature and volume of the suspension passing therethrough, it being understood however that such cooling is not essential and may be omitted.

From cooler 45 the gaseous suspension passes by line 46 to ya suitable gas-solids separator, or preferably a series of such separators suc-h as cyclone separators or the like 41a, 41h and 41e. In each of these a part of the suspended particles is separated and withdrawn from the bottom of the separators through tail pipes 43a, 48h and 48e. Material discharged from these tail pipes may be conveyed to a regenerated catalyst recovery vhopper 49 through lines 50a, y5017 and l50c by way of transfer line l by means of a suitable uid conveying medium, such as steam, supplied by jets through lines 52a, 521) and 52e.

From separator 41a the suspension passes by line 52 to a Cottrell precipitator 53 or other suitable means for separating the extremely fine pai'- ticles from the gaseous suspension, the separated particles being collected in the bottom hopper 54 of the precipitator, land the separated gas exciting overhead to the atmosphere through line 55.

Cottrell precipitator 53 is preferably operated under approximately atmospheric pressure, and a pressure reduction valve may be provided in line 52 for regulating the pressure so that the desired pressure may be maintained in separator 53 irrespective of the pressure in the discharge line leading from cyclone 41a. v

A continuous stream of previously separated relatively coarse particles preferably is supplied to a mixing zone in hopper 54 through line 56 from hopper 24 for the purpose of mixing with and bringing the iines to a condition which may be described as flowable Coarse particles for this purpose supplied through line 56 may be supplemented by fresh or make-up" catalyst Supplied to the system from hopper 51 through line 58. place unavoidable losses of catalyst from the system and to compensate for yany gradual permanent decrease in activity of the circulated catalyst. An aerating medium preferably is supplied,

to the bottom of the hopper 54 by means not shown, but similar to elements 21 and 28, for aerating the mixture therein and maintaining it in a readily flowable condition.

From hopper 54 the aerated mixture iiows intoy Such make-up catalyst is necessary to rel0 charged by means of a suitable valve such as a slide valve 6I into transfer line 5l. Steam or other suitable conveying medium is supplied by line 62 to line 5l to convey the mixture to hopper 49 or if desired to any other zone.

In passing through line 5l the mixture is combined with the streams from lines 59a, 56h and 50c and passes to collecting hopper 49 wherein the combined fractions are separated in the bottom of the hopper, and the gaseous suspending medium is separated overhead through line 63 and passes into line 46 leading to the cyclone separators. From'hopper 49 the separated solids are withdrawnthrough a standpipe 64 operating on a principle similar to standpipes 30 and 59 and to which a suitable aerating medium is supplied through lines 65. standpipe 64' is preferably of a height suiiicient to balance the difference in pressure between hopper 49 and hopper 24. From standpipe 64 the solids are fed through a slide valve 66 intovtransfer line 26 wherein they are suspendedby suitable conveying fluid such as steam supplied through line 61 and conveyed therethrough to hopper 24 and combined with the initially separated material.

The operationof the regenerated catalyst recovery system may be further exemplied by reference to conditions obtained in the specic regeneration operation illustrated by Table 2-A. Pursuant to this example, the proportions of ref generated powdered cracking catalyst separated inthe various ,separating zones, based upon the quantity of material entering the system through line I9, were .approximately as follows:

The percentage recovery in hopper 24 based upon the total solids passing through outlet 23 including the recycled catalyst from line 30, is substantially greater than on the above basis, amounting to about In this example, pressure conditions obtained throughout the regeneration system were approximately as follows:

Pressure,

Zone Lbs/sq. In.

Regenerator 2l (base) In this particular example, the lines collected in hopper 54 were mixed with relatively coarse particles introduced through line 56 in about equal proportions. Obviously in certain instances the addition of more or less coarse particles through line 56 may be necessary for best results.

13 |02, and bottoms withdrawn from the system through line I I I. Additional steam may be added to the feed vapors in line 3 through line I II).

In the foregoing a preferred procedure and arrangement of apparatus for practicing the invention has been described; however, it will be apparent to those skilled in the art that various modiflcations thereof may be made without departing from the essential features of the invention. For example, the movement and circulation of the catalyst to and from the various Zones may be effected by solids pumps suchl as vdescribed in Kinyon Patent 1,553,539 in place 'of catalyst standpipes. Also, other types of gas-solids separating means for recovering finely divided solids from the gaseous products withdrawn from the conversion and regeneration zones may be substituted for those shown.` The fresh or regenerated catalystneed not be introduced into the conversion zone in mixture with the feedvapors, but may be introduced separately as for example by providing a separate line interconnecting the bottom of standpipe yCvI and reactor 6 and conveying the catalyst therethrough by a suitable medium such as steam, or standpipe 3l may terminate directly in the base of reactor 6. By a further modification the withdrawal of used catalyst as well as the addition of spent catalyst to the reactor may be effected through inlets and outlets separate from those utilized for the introductionand with.- drawal of vapors, as for example by a process flow such as that shown in Fig. 3.

.Certain Variable operating conditions in the practice of the process may follow and be controlled pursuant to conventional practice in the art of vapor phasecatalytic cracking' o'f high boiling hydrocarbons, including such factors as the selection of suitable charging stock, catalytic material, conversion temperatures, and pressures.

Primary operating variables distinctively controlled, pursuant to the present invention, are the rate of feed of the high boiling hydrocarbons and the rate of feed of the catalyst'to the Yreaction Zone and the weight of catalyst inv said zone.

The rate of feed of the hydrocarbon charge to a reactor of given dimensions is maintained within such limits that the upward velocity ofthe vapors through the zones is relatively low and sufficient to form a dense phase or mass of catalyst therein. Conversely, 4for the conversion of a given quantity of charging stock in a given unit of time, the cross-sectional area of the reactor must be of the dimensions required to provide the desired low vapor velocity therein.

The rate of fresh catalyst feed is dependent upon the desired average catalytic activity of the dense phase of catalyst in the conversion zone, and fresh catalyst is continually added at a rate adapted to maintain such activity at the desired value as the conversion proceeds. Used catalyst is Withdrawn at the same average rate as fresh catalyst is added, therefore, the average time a catalyst particle remains in the reactor (catalyst resident time) is determined by the catalyst feed rate and maybe calculated by dividing the weight of catalyst in the reactor by the catalyst feed rate per minute. The concentration y (density) of catalyst in the dense phase is dependent primarily upon the particular low vapor velocity maintained. Within limits, an increase or decrease of the rate of catalyst feed apparently has no substantial or Asignificant effect on the concentration (density) of the dense phase. A further factor effecting the optimum feed rate of catalyst to the conversion zone is ya condition which may be termed the catalyst level phenomenon. Dependent upon the height of the reactor and with low velocities, two distinct phases of catalyst concentration are present in the reactor, a lower dense phase and an upper phase wherein the concentration of catalystis relatively very dilute, the boundary or interface between the phases being at a horizontal plane intermediate the vapor inlet and outlet. It has been ascertained that the distance of this interface from the top outlet 'I in reactor 6, other conditions being xed, is dependent upon the rate of catalyst feed and that the magnitude of this distance varies inversely with the rate of catalyst feed. Accordingly, the rate of feed is normally and preferably regulated or, a fixed catalyst feed rate being assumed, the height of the reactor xed) so that the upper level of the dense catalyst phase will be confined to the upper part of the reactor, this level or interface being indicated in reactor 6 by dotted line A and in regenerator 2| by dotted line B.

The weight of catalyst in the reactor (a Xed height of reactor being assumed) is dependent upon the concentration of the dense phase (in turn dependent primarily upon the particular low velocity maintained) and the distance of the upper level of the dense phase from the upper vapor outlet (the latter in turn being dependent upon the catalyst feed rate).

Accordingly, proceeding on the above noted principles pursuant to this invention, the rate of feed of hydrocarbon vapors and rate of feed of the catalyst to the conversion zone are preferably controlled within such limits that the vapors of the high boiling hydrocarbons flow upwardly through the conversion zone at a velocity sufliciently low to form a dense phase or mass of the catalyst in said Zone, and fresh catalyst is added to said dense phase and corresponding amounts of used catalyst withdrawn therefrom at a rate adapted to maintain the average catalytic activity of said mass of catalyst at a suitable value and preferably also at a suitable rate to maintain the level of said dense phase within the confines of the upper part of the reaction zone.

The effect of variations in the several operating conditions over a wide range is disclosed by the illustrative runs given in the following table 4. In these runs the feed stock consisted of a 35 A. P. I. Mid-Continent gas oil having an initial boiling point of 470 F. and end point of 736 F. (A. S. T. M.). rlhe catalyst employed Was a silica-alumina type of cracking catalyst consisting of powdered super-Filtrol, the particle size distribution of the catalyst being approximately 10% 0-10 microns, 20% 10-20 microns, 20% 20-30 microns, 20% 30-40 microns, and 30% 40+ microns. In Table 4, the ratio of the weight of catalyst feed per hour to the weight of oil feed per hour constitutes the cat/oil weight ratio. Catalyst resident time .cat. time mins. for both reactor and regenerator was calculated by dividing the weight of catalyst in the reactor by the catalyst feed rate perI minute. The vapor velocities at the inlet of the reactor were calculated on the assumed basis that the catalyst volume Was negligible. The outlet vapor velocity was calculated on the basis of the outlet conditions of temperature and pressure, and mols of product produced. The arithmetical average of inlet and outlet velocities was divided by the reactorl length to obtain the superficial oil contact time (oil time) Y 2;..l1..,..&4

TABLE" 4 1 36 A. P. I, Mid- Continent Gas Oil-.GutalystSuper-Film1 u.. 4 .s um... .s e Er s; t S @E 35@ Velvet-Y 5;' g3 y51 e 5- j 5: y H Y o H l O' Runnumber `Qn'.r 5E" g1g d O E 3 j g d 05 C Ff" .fg e. m

'se5 ofso@ s am .im cosa.- n a eg eze @se .55, .io- LE O .A o. o. 3 B. l.. oy o Reactor-Vertical l'ln; z l2 Fi. Tubew [inn/w. Greater Then 3,04

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Reactor-,.-Verticcll In. 21.12 Ft. Tuberba/hn/w.

1. 5.. 4. 9y 68. 2 8.2I 13. 2 9. 2 0. 47 0. 67 1. 15 17. 0 49:v 7^ 31g8 12g 3 7; 6 7:16 1. 7 2. 3 65. 9 15. 34 s; 5 17. 2 0. 70 1. 1v 1.6 15. s 4.6.. 9. 3 4. 1. 12,2 6,5 9.0 1*.7 2:9' 65. 6` 12:3 8. 2'- 17.5 0.52 1. 1 1. 7 15. 8- 47. 5 34. 4 12. 0 7. 7- 7. 4 2. 2, 2.7 5 9. s. 9. 9, 4. 1 37.4 0. 39 "2.6 5 3 f 11. 2 45. 7 4o. 2 1 1. 4, 6 4. 5 1. 6 3:3' 64. 8 11. 2 16. 5 0. 0 0. y56 0. 4 3 0.95. 16.7v 47,10 3.5. 3, 9. 8. 1 8. 0 Z 9 2; 8 59.2 7: 4 8; 2j 8:3 74 1. 1 1. 7 14.*6 45. 3 40. 8" 10. O 6. 0 5. 6 1 2h 2. 3y 65. 9 2 1, 9 1 1. 4 10. 3 1. 84 0:81' 1.; 3 21. 9v 45. 4 y 34. 1 10. 3 7. 2j 10. 7 1. 7 2. 8 72. 5 12. 6 12. 9 10. 5 0.59. 0. 7 1. 1 15. 2 51.6,- 27. 5. 13, 3 8.1 9.v 2 1'. 6 3;4, 72:5 11. 4v 12. 9l 10. 3 0.' 50 0. 7" 1. 1 16.4 53. 3 27. 5 12:0 7. 5- 9. 1 0. 74 4. 0, s2. o 20.5 2 0. 7 9. 6 o, 5s 0,45V o. 7 17; 6 5o.; 6 18. 6 16.0, 9. 1 16.6 0. 75 4. 3 80. lv 18. 6 20; 8 9. 9 0. 53 0. 43.y 0. 71 17. 0 13./8.,. 19. Q 16. 5 8 7 Fromthe specic examples given it willbe evident that an operatingcondition of primary importance in the practice of the invention is the relatively low velocity and resulting high concentration of catalyst maintained in the conversion and regeneration stages. Referring for example, to Table l-A it will be noted that the catalyst concentration in reactor'GWa-s 18 lbs. per cu. ft. as compared with a catalyst concentration of about 1; l b. per cu. ft. in the reactor inlet line 2. Under suchhigh concentration conditions, the 110W of the catalyst may be described as that of a compacted turbulent mass or moving bed.

' In order to provide this dense orV concentrated phase of the catalyst in the conversion and regeneration stages, low vapor velocities o f the ordei' off-about 6 ft. per second or less, and preferably of about 4 ft. per second or less are contemplated. Vapor velocity ranges regarded as especially suitable for the practice of the process in vertical reaction vessels of the type shown in Fig. 2. are about 6 to 0.5 ft. per second, preferably about-1.5 to 2 ft.l per second. Even lower Vapor velocities than these indicated minimums may be utilizedfto advantage with the modified type of conversion system illustratedin Fig. 3.

Itis further contemplated that the practice of the process, under most conditions, maybe satisfactorily effected, utilizing a catalyst to oil feed weight ratio Within the range of-about' 0.5:1.0 to 2021.0 and preferably-Within the more-restricted range of about 2:1 to 8:1, and with a Value of W./hr-./w. Within the range of about 1.0 to 25.0 andpreferably Within the more restricted. range of about 2.5| to 10.0.

The -modifled-process flow iIllustrated in Fig. 3 differs.fromy thatof-Fiss.- 1 and `2 in that tho-Catolyst isintroduced. toY and Withdrawn from the conversion zone.- and, regeneration; Zoneby catalyst inlets and .outlets .separate -from the-inletand outlet 'for al1 or the.Illa-icmV proportion ofthe va.- porsl undergoing conversion, or the regeneration fluid.` Elements 0f.- Fisg., 3 having a generally similar function to those; described in detail infcone nectiprrwithFigs, 1 and zare-designated in Fig. 3 With-L a similarnumeral with the suliix. 1 and hencedetailed descriptionoi theseelements is superfluous. Operating variables likewise may be controlled for this processv W pursuant to the principles disclosedin connection with Figs. 1 and'z, Feed-vapors are introducedrthrough line 3c and a suitable manifold 5a substantiallyv u niformly throughout the bottom area oi the reactor so that. the dense phase o` catalyst thereinis maintained in an aerated fiowable, condition. Rosonerated' catalyst. from. sto-norme 39a. is in..- troduced by a current .oiga sintable conveying me@ diurn, such as-steam.- (or a mix-ture of steamY and part of the feed vapors supplied through line H4). through. catalyst inlet line la` and flows. laterally throughy the reactor transverselyv to the entering vapors, and is Withdrawn at the opposite side of the.- reactor at acontrolled rate throughstandpipe Ita by means of valve |8a. The height oflevel of the denso phase of catalyst in the-reactor Ea is regulated by operation of valve 18a, and in this respect dit-fers from the flow described in connection with Fig.v 2. The horizontal level of the dense phase of catalyst is preferably maintained below the. vapor. outlets; 8.2. at o suitable 17 distance to provide-1a suiilcient catalyst-vapor disengaging space such that only a relatively small minimal amount of the usedfcatalyst is carried overhead `with the Vapor through line i3d.

18 i ticles to said dense phase and withdrawing corresponding amounts of used catalyst therefrom at a rate in excess of a catalyst-to-hydrocarbon feed .f

Weight ratio of about two to one and adapted to` produce and maintain the bed and its averagesy catalytic activity at a suitable value and 'itsupper meniscus at a height to provide the ratio l rator I I2 and returned byline II3 to the reactor i at the steam stripping zone above thecatalyst l.

standpipe outlet I Ia. Similarly in the regeneration zone, the spent catalyst is introduced thereto by a separate outlet I9 from standpipe I Ia and withdrawn at the opposite end of the regeneration zone by a separate outlet standpipe 30a. The

level of catalyst in the regeneration zone is con-" trolled in the same manner as in the conversion zone so that only a relatively small amount ofv catalyst passes out of the zone overhead through the outlets 23a to the gas-solids recovery system.

The vapor velocities used in this type of process oW may be quite low, the limiting quantity being that required to maintain the body of catalyst in an aerated or owable condition.

Any of the various known types of cracking catalysts may be utilized in the practice of the invention. The preferred catalysts are those of the silica-alumina, -or silica-magnesia type adapted to produce a Satisfactory yield of high octane gasoline. Either silica-alumina catalyst consisting of activated clay prepared by the acid treatment of natural clays, for example the commercial product Super-Filtrol or a synthetically prepared silica-alumina catalyst such as those disclosed in copending applications of Robert Ruthrufl", Serial Nos. 305,472 and 305,473, both filed November 21, 1939, which have issued as Patents Nos. 2,391,481 and 2,391,482, respectively, both dated December 25, 1945, may be employed. The catalyst is preferably employed in finely divided or powdered condition, for example with particles ranging from about 1 to 100 microns. Other conditions such as temperature, pressures,` feed stock, and the like, maybe selected and controlled pursuant to conventional practice in the art of vapor phase catalytic cracking of high boiling hydrocarbons. f v

We claim:

1. A continuous process for the catalytic cracking of high boiling hydrocarbons to low boiling hydrocarbons within the gasoline boiling range which comprises introducing a cracking catalyst of small particles within the dimensional rangev of about 1 to 1 00 microns to a catalytic conversion zone of relatively large cross-sectional area with reference to the cross-sectional areas of the inlet for the hydrocarbons in the lower part of the zone and the vaporous products outlet in the upper part of the zone, owing vapors of the high boiling hydrocarbons undergoing cracking upwardly through said zone at a velocity within the range of about 0.5 to 6 feet per second and adapted, in combination with the continuously maintained minimum catalyst-to-hydrocarbonv feed weight ratio hereafter' specified, continuously to form and maintain in said zone a dense turbulent bed of the catalyst particles having a density not substantially lower than pounds per cubic foot and having a distinctl upper level or meniscus belutefcontinually introducing active-catalyst parrequired for the desired conversion, of weight of hydrocarbon fed per hour tor weight of catalystvv in the conversion zone less than 25: 1. Y,

2. A continuous process for the catalytic cracking of high boilinghydrocarbons to low .boilingl hydrocarbons within the gasoline boiling range which comprises introducing 'a crackingcatalysti;

of small particles within the dimensional range of about l to microns to a catalytic conver-w-f' sion zone of relatively large cross-sectional areas. with reference to the cross-sectional areas of thel inletv for the hydrocarbons in the lower part-off;

the zone and the vaporous products outlet in the g upper part of the zone,v flowing vapors of the high,V boiling hydrocarbons undergoing cracking -upl wardly through said zone at a velocity within the range of about 0.5 to 6 feet per second' and*- adapted, in combination with the continuously@ maintained minimum catalyst-to-hydrocarbon 1 feed weight ratio hereafter specified, continu-i ously to form and maintain in said zone a denseV turbulent bed of the catalyst particles having a density not substantially lower than 5 pounds per cubic foot and having a distinct upper level.; or meniscus below the vaporous outlet aboveJ which meniscus the concentration of catalyst-=A suspended in the outwardly flowing vapor stream is relatively dilute and corresponds' to a density@ not substantially greater than l pound per cubic foot, continually introducing active catalyst par-- ticles to said dense phase and withdrawing corresponding amounts of used catalyst therefrom at a rate in excess of a.'catalyst-to-hydrocarbon feed Weight ratiol of'about two to one and adapted in the conversion 'Zone less than 25:1.

3. A continuous process for the catalytic crack-1'* ing of high boiling hydrocarbons to low boiling -hydrocarbons within the gasoline boiling range which comprises introducing a cracking catalyst# of small particles withinthe dimensional 'range'l of about 1 to 100 microns to a catalytic conver-f sion zone of relatively large cross-sectional area" iwith reference to thecross-sectional areas of theinlet for the hydrocarbons in the lower part of the vzone and the vaporous products outlet in'thefl upper part of the zone,flowing vapors of the high *f boiling hydrocarbons undergoing cracking upwardly through said zone at a velocity within they range of about 0.5 to 6 feet per second and` feed weight ratio hereafter specified, continuously f" to form and maintain in said Zone a dense turbulent bed of the catalyst particles having a dis-'1 tinct upper level or meniscus below the vaporous f outlet above which meniscus the concentration of catalyst suspended in' the outwardly'iiowing4v` vapor stream is relatively dilute, continually in-" troducing active catalyst lparticles to said dense?" phase and withdrawing corresponding amounts. of used catalysttherefrom at a rate in excess of? a catalyst-to-hydrocarbon feed Weight ratio/fof:l about two to one and adapted to produce and@ andere:

-ISE

' liiaiifitai1i:v 'the-bediand its average catalytic activityat' a suitable value andy itsv upper IneniscusV at; a heighty toprovide the'- ratio required. for.= the'de.- sirediconversion, ot weight of hydrocarbon ted' per hour to weight of catalyst in the conversion zone less=than 25:1

421A continuous processr for the catalytic.' cracking-` of high boiling hydrocarbons to lowboiflinghydrocarbons within the gasoline boiling range which comprises. introducing a cracking` catalyst ofsmall particleswithin the dimensional range-of about ll to 100 microns to a catalytic conversion zone. of relatively large cross-sectionals area with reference to the cross-sectional* arll'eas*A oil'the inlet for the hydrocarbons in the: lower'part of! the zone Y and' the- Vaporous products: outlet in thel upperr part of the zone, flowing vapors ofthe high boiling lhydrocarbons undergoing-cracking upwardly through said zone ata velocity within the range of aboutl 0.5 to 6l feet, perA secondv andadapted; in combination. with the continuously maintained.` minimum' catalyst-tol-v hydro-carbon feed*l weight ratiol hereafter speci-1 fied; continuously` to forni and maintain in said zone-"3, dense turbulent bedioff the catalyst partitles: having ai distinct upper level or meniscus" below'th'e vaporousfoutlet. abover which meniscus the concentration. off` eatalystsuspended in the outts'lardlyy flowing vapor stream is relatively dilute?,` continually introducing active catalyst. particles tasa/id? dense phase and withdrawing corresponding amountsl ofl used' catalystA therefrom at'r a rate in excessi ofl a catalyst-toehydrof-l carbon Yf'eed' weigh-ti ratio of'r about two to one! and' adapted to` produce and maintain the bed andi its'. average catalytic activity at a suitable,v value1' Aand its upper" meniscusV ata height-to provideltlieratiorequired for the desired conversion,v oiw'eightof hydrocarbon! fed per hour to weight; ofcatalyst inthe conversion zone less than 10:-1.

5JAtfc'ontinuous processfor cracking hydro-V1 carbon oils. involving cyclically circulating cata-,1`

lyst(` through a hydrocarbon conversion zone in contactv with the oit component in the gaseousl phasea'ndf ai catalyst regeneration zone-in con-. tactwith an oxygen-containingv gas compo-nent; said zones havingj alrelatively large; cross-sem` tional areal relative-to, the cross-sectional areas oftli'e. inletfor ther incoming gasicomponent: in-l the lowerI portion:` thereof and' the outlet forr ther outiowi'ng gas component inthe 11p-per' portiony thereof, introducing a catalyst for said cyclic` circulation of? small particles within the dimen. sional range of aboutY 1- to 100: micronsv and 'inf c1ualr'itity as specied hereafter, flowingA the gas componente upwardly through. said com/ersicn and:1 regenerationv zones ata velocityi within the range ofi about 0.*5. to 6% feet per second and adapted; in combination with the introduction; of` a: quantity' oi" catalyst and the continuously maintainedminimum catalyst-to-oil feed? Weight ratio; Specied hereafter-,- continuously to l form` andi maintain in bothv said zonesa, densetultbulent; bedr oir the catalystl particlesV having a dis--` tinct'fupperlevel or meniscusbelow the outlet forf'the gas component above-f` which meniscu-s; the;concentration` of catalyst: particles suspendedV im'thef ontilowing.r gas component is relatively:` dilute; introducingthe cyclically circulated4 cata lyst particles and" cyclicallyl circulating them' through the conversion andy regeneration zones at` mirate-in excess of; that corresponding to: a ca ta'f lystetoehydrocarbon feed:- weight; ratio the conversion zone of about twov to one,l and" in'` amounts: respectively regulated to, maintain: the 715'; below the; outlet; for the gas component; above.

20. upper meriiscus ineach 0f said zonesat a desirable height for the-reaction effected therein and maintainfinj the conversionr zone a quantity ofV catalyst corresponding to a ratioy of hydro;- carbon fed; per hour to weight of` catalyst in the conversion zonelessthan 25:1.

6.'. A: process in accordance with claim 5v iurther; characterized by withdrawing catalyst from atleast one of the dense turbulent beds offthecatalyst particles and introducing an inertl gaseous. iiuid-intoqcontactwith the thus withdrawn,V

the vaporous products `outletin the'upper part,Y

of the zone, iiowing: vapors of the high boiling: hydrocarbons undergoing cracking upwardly through saidl zone at a velocity within thefrange ofv about' 0:5 to 4I feetr per second and adapted.; inv-.combination with the continuouslyl maintained' minimum catalyst-to-.hydrocarbon feed' weight ratio hereafter specified, continuously to form andfma-intain in saidzonefa dense turbulent bed; ofthe catalyst particles having a distinct upper level5 ormeniscus below the vaporous outletabove' which' menis'cusr the. concentration of Acatalyst suspended in the outwardlyiiowing vapor stream isf relatively dilute, continually introducing active catalyst'particles tofsaiddense phase and Withdrawing-'corresponding amounts of used catalyst thereiromat a rate in excess of a catalyst-tohydrocar'bon feedl weight ratioof about two to one and adapted to produce and maintain the bed and its average` catalytic activity at a suitable Value and its upper meniscus` at a height toprovide the ratio required for the desired conversion, to weight of hydrocarbon fed per hour to weight of' catalyst in the conversion zone less than 25:1.

8. A continuous process for cracking hydrocarbon oi-ls involving' cyclically circulating catalyst through a hydrocarbon Aconversion zone in contact with the oil component in the gaseous phasevand a catalyst regeneration zone in contact withy an oxygen-containing gas component, said zones' having a relatively large cross-sectional area relative to the cross sectional areas ofi the inlet for the incoming gas component in the lowerportion thereof and the outlet for the outo'w'i'ng gas component in the upper portion thereof,` introducing a catalyst for-said cyclic cir'- culationf ci" indiscriminately sized small particles within the dimensional' range ofv about l to 100L microns and in quantity as specified hereafter; owing the gas component upwardly through said conversion and regeneration zones atA a velocity within the range of about 0.5 to 6 feet persecond and adapted, in combination with the` introduction or ai quantity of catalyst and the continuouslyl maintained minimum catalyst-tooilefeecl` weightratiovv as specifiedy hereafter, continuousllyfto formY and maintainv in bothI said zones a; denseturbulent bed of the, catalyst'par ticles having,- a= distinct upper level or meniscus which meniscus the concentration of catalyst particles suspended in the outowing gas component is relatively dilute, introducing the cyclically circulated catalyst particles and cyclically circulating them through the conversion and regeneration zones at a rate in excess of that corresponding to a catalyst-to-hydrocarbon feed weight ratio in the conversion zone of about two to one, and in amounts respectively regulated to maintain the upper meniscus in each of said zones at a desirable height for the reaction effected therein and maintain in the conversion zone a quantity of catalyst corresponding to a ratio of hydrocarbon fed per hour to weight of catalyst in the conversion zone less than 25:1.

9. A continuous process for cracking hydrocarbon oils involving cyclically circulating catalyst through a hydrocarbon conversion zone in contact with the oil component in the gaseous phase and a catalyst regeneration zone in contact With an oxygen-containing gas component, said regeneration zone having a relatively large crosssectional area relative to the cross-sectional areas of the inlet for the incoming gas component opening into the lower portion thereof and the outlet for the outflowing gas component in the upper portion thereof, introducing a catalyst for said cyclic circulation of indiscriminately sized small particles within the dimensional range of about 1 to 100 microns and in quantity as specifled hereafter, owing the gas component upwardly through said regeneration zone at a velocity Within the range of about 0.5 to 6 feet per second and adapted, in combination with the introduction of a quantity of catalyst and the continuously maintained minimum catalys-t-tooil feed weight ratio as specified hereafter, continuously to form and maintain in the regeneration zone a dense turbulent bed of thecatalyst particles having a distinct upper level or meniscus below the outlet for the gas component above which meniscus the concentration of catalyst particlessuspended in the outowing gas cornponent is relatively dilute, introducing the cyclically circulated catalyst particles and cyclically circulating them through the conversion and regeneration zones at a rate in excess of that corresponding to a catalyst-to-hydrocarbon feed weight ratio in the conversion zone of about two to one, and in amounts respectively regulated to maintain the upper meniscus in the regeneration zone at a desirable height for the reaction effected therein.

10. A process as dened in claim 9 wherein the exothermic regeneration zone is maintained at a higher temperature level than the endothermic conversion zone, and the cyclically circulated catalyst serves to absorb heat in the former and supply heat in the latter.

11. A process as defined in claim 9 wherein a portion of the regenerated catalyst Withdrawn from the regeneration zone is cooled and directly returned to the dense turbulent catalyst bed for temperature control thereof.

12. A continuous process for converting hydrocarbon oils involving cyclically circulating catalyst through `a hydrocarbon conversion zone in contact with the oil component in the gaseous phase and a catalyst regeneration zone in contact with an oxygen-containing gas component to burn off carbonaceous deposits formed on the catalyst in the conversion zone, said zones having a relatively large cross-sectional area relative to the cross-sectional areas` of the inlet for the incoming gas component in the lower portion thereof and the outlet for the outflowing gas component in the upper portion thereof, introducing a catalyst for said cyclic circulation comprising non-uniform sized small particles within the dimensional range of about 1 to 100 microns and in quantity as specified hereafter, flowing the gas component upwardly through said conversion and regeneration zones at a velocity within the range of about 0.5 to 6 feet per second and adapted, in combination with the introduction of a. quantity of catalyst and the continuously maintained minimum catalySt-to-oil feed weight ratio as specified hereafter, .continuously to form and maintain in both said zones a dense turbulent bed of the catalyst particles having a distinct upper level or meniscus below the outlet for the gas component above which meniscus the concentration of catalyst particles suspended in the outflowing gas component is relatively dilute, introducing and cyclically circulating catalyst through the conversion and regeneration zones at a rate in excess of that corresponding to a catalyst-to-hydrocarbon feed weight ratio to the `conversion zone of about two to one, and in amounts respectively regulated to maintain the upper meniscus in each of said zones at a desirable height f`o"r the reaction elfected therein and maintain in the conversion zone a quantity of catalyst corresponding to a, ratio of hydrocarbon fed per hour to weight of catalyst in the. conversion Zone less than 25:1, and maintaining the turbulent catalyst bed in the exothermic regeneration zone at a higher temperature level than the said bed in the endothermic conversion zone wherebythe cyclically circulated catalyst serves to absorb heat in the former zone and supply the absorbed heat in the latter zone.

13. A process as defined in claim 12 wherein the maximum velocity maintained in said zones isabout 4 feetl per second.

PERCIVAL C. KEITH. JOSEPH W. JEWELL.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 1,984,380 Odell Dec. 18, 1934 2,231,231 Subkow Feb. 11, 1941 2,300,151 Hemminger Oct. 27, 1942 2,319,710 Stratford et zal May 18, 1943 2,387,088 Oblad et al Oct. 16, 1945 

7. A CONTINUOUS PROCESS FOR THE CATALYTIC CRACKING OF HIGH BOILING HYDROCARBONS TO LOW BOILING HYDROCARBONS WITHIN THE GASOLINE BOILING RANGE WHICH COMPRISES INTRODUCING A CRACKING CATALYST OF INDISCRIMINATELY SIZED SMALL PARTICLES WITHIN THE DIMENSIONAL RANGE OF ABOUT 1 TO 100 MICRONS TO A CATALYTIC CONVERSION ZONE OF RELATIVELY LARGE CROSS-SECTIONAL AREA WITH REFERENCE TO THE CROSS-SECTIONAL AREA WITH REFERENCE TO THE CROSS-SECTIONAL AREAS OF THE INLET FOR THE HYDROCARBON IN THE LOWER PART OF THE ZONE AND THE VAPOROUS PRODUCTS OUTLET IN THE UPPER PART OF THE ZONE, FLOWING VAPORS OF THE HIGH BOILING HYDROCARBONS UNDERGOING CRACKING UPWARDLY THROUGH SAID ZONE AT A VELOCITY WITHIN THE RANGE OF ABOUT 0.5 TO 4 FEET PER SECOND AND ADAPTED. 